判断下列各句中用括号括起来的代词照应是否错误，错的请改正
1）.When the ship started,(it) was shaking.
2).Failure is the mother of success,and (it) is true.
3).(That)'s my opinion:you should study (it).
4).You should keep calm when (we)'re in danger.
5).Be like (that).Open your mouth and drink (it).
6).The weather of ShenZhen is better than (this) of Guangzhou.
7).The fruits of ShenZhen are better than (these) of Guangzhou.